數位內容的安全群播服務近來已成為越來越重要的多點傳輸應用，這導致了一些新的金匙管理技術研究。金匙管理問題的研究中有一個著名的，使用金匙樹的WGL方法。WGL方法雖然解決了向後安全和向前安全的要求，但卻有金匙數量過於龐大，導致儲存空間過大和人員異動帶來的計算、通訊成本過高的缺點。在這篇論文中我們提出了一個基於法團式秘密分享技術的嶄新方法來完成多點傳輸金匙管理。利用法團式秘密分享，我們設計出一個新的通訊協定，達到向後安全和向前安全的要求。理論分析顯示，我們的方法在儲存空間的需求和加入新用戶所需的計算和通訊成本上都優於WGL方法。至於舊用戶離去所需的計算和通訊成本，WGL方法較好；不過我們的方法分散化與平行化程度較高，若採用平行運算或叢集技術，將可有效改善這項缺失。

Multicast streaming service is one of the prospective killer applications in Internet. Secure group communication, which provides confidentiality, authenticity, and integrity of messages delivered between group members, will become an interesting and critical issue in multimedia delivery services in the near future. Several techniques have been proposed to solve this problem, among them, the key management problem is the most important one, which can maintain the group state dynamically and protect the improper access and unauthorized playback as well.
There is a famous solution of the key management problem that uses key tree graph (WGL scheme). Although the WGL scheme solved the backward and forward secrecy problem, but the number of keys that WGL scheme needs is too large. This results a large storage requirement and high computation and communication costs causing by membership changes. In this thesis, a novel method based upon the quorum secret sharing scheme to solve the key management problem is presented. In addition, a corresponding quorum-secret-sharing based protocol that can fulfill the backward and forward secrecies is also proposed.
The theoretical analysis shows our method is better than WGL scheme in the storage requirement and the computation cost as well as the communication cost for JOIN. For the LEAVE operation, our method is worse than WGL, however, we address that we may use parallel computation or cluster technique to improve it because the level of distribution and parallel of our method are higher than WGL scheme.

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